The present invention relates generally to aircraft positioning systems, and more particularly to a system and method for validating a position of an aircraft with cross-referenced information sources.
A major cause of aircraft accidents is the failure of an aircraft's positioning systems to adequately alert pilots of their true position, especially relative to variations in the terrain around them, such as with hills and mountains. Recent advances in aircraft navigation systems have done much to alleviate the problem of making a pilot aware an aircraft's position relative to terrain elements. Specifically, U.S. Pat. No. 5,839,080, owned by AlliedSignal, describes a terrain awareness system (TAS) to alert a pilot to terrain threats within a proximity of the aircraft. Further, Allied Signal's Enhanced Ground Proximity Warning System (EGPWS) provides a display of potentially hazardous terrain in an area surrounding a position of the aircraft as that position is reported by the flight management system (FMS) and/or other on-board navigation systems, such as a global positioning system (GPS) receiver. The terrain data is retrieved from a terrain database, such as a digital terrain elevation database (DTED).
Two sources of error may exist in conventional aircraft positioning systems. First, there may be errors in the terrain database. Second, there may be errors in the aircraft's reported position.